Sahara's Ancient Network of Drainages and Streams (SANDS) : The Libyan Testimony

Abstract

Libya lacks a permanent natural body of water, causing it to rely on fossil water from underground aquifers that originate more than tens of thousands of years ago. The ancient aquifers are a relic from a time when the Sahara was green and home to rivers and lakes. Since this water is not naturally replenished, there is an increasing need to explore more sources of fossil water under the Sahara's sands. Remote sensing data from the Phased Array L-band Synthetic Aperture Radar (PALSAR) sensor, onboard the Advanced Land Observing Satellite (ALOS), has been shown to penetrate and reveal subsurface features up to several meters deep. This is especially useful in regions such as Libya, where dry, shallow sand cover allows effective PALSAR’s L-Band Penetration. PALSAR, along with optical remote sensing and topographic data within the Google Earth Engine platform, provides new capabilities to conduct multi-level spatial analysis. Preliminary results reveal a previously unidentified and/ under-appreciated network of ancient drainages, streams, and small-scale deltas or alluvial fans, many of which are connected to previously identified megalakes. These findings will provide valuable insight into the region's ancient hydrological system and its potential for future water resources.